This is a revision of Core B, the Animal Models Core. Both reviewers expressed a high level of enthusiasm for the development of this new core and the services it will provide to the individual investigators. It was voted for approval. Reviewer one raised a minor concern. The reviewer requested that information be given about the specific breeding and delineation of mouse lines. We now include this information in a new Section II entitled: "Description of Mouse lines to be used in individual projects," and is indicated by bold print. The original Core II (Use of Animal Core by Individual Projects) is now Section III. In addition, we are now collaborating with Dr. Craig Basson, a Professor of Medicine and Cell and Developmental Biology and the head of the Laboratory of Molecular Cardiology. His laboratory has extensive experience on performing and interpreting echocardiographies on small animals, and has agreed to assist Dr. Kraemer in interpreting the echocardiograms of mice which have undergone LAD occlusion/reperfusion (See attached letter). The Animal Models Core will provide three basic services: A. Breeding, genotyping and caring for mouse lines to be used in individual projects. B. Surgical services for in vivo models of murine cardiovascular injury. C. Training of personnel from individual laboratories for the histological and morphological analysis of injured tissue. A description of each aspect of the Animal Models Core is provided below followed by an assessment of the use of this core by individual projects. The Animal Models Core will provide three basic services: A. Breeding, genotyping and caring for mouse lines to be used in individual projects. B. Surgical services for in vivo models of murine cardiovascular injury. C. Training of personnel from individual laboratories for the histological and morphological analysis of injured tissue. A description of each aspect of the Animal Models Core is provided below followed by an assessment of the use of this core by individual projects.